"With iOS 9, core IMAP apps such as Reminders, Calendar and Notes will now also feature an iCloud back-end. This will shift the apps from IMAP servers to Apple’s iCloud servers, touting improved syncing and end-to-end encryption." http://wccftech.com/ios-9/If Notes had reliable syncing, then it would have been a good alternative. But as it is now, no, not at all.
I have got burned by Notes.app sync. More than one time. But I have faith in the new Notes.